I like Def based armors in general. I like them more on Scrappers. /stone would be awesome, but even trying to minimalize it might not lead to the desired results. /sr, /nin, and /ea are far easier to pull off. /nin, and /ea offer End management. My /nin is too low to really comment, but I have /ea at 50 already twice with a third at 38 covering Stalker, Scrapper, and Brute. It's fantastic. Before getting the Energize isn't as bad as one might think for not having a heal as /ea can put up solid enough Def numbers.
For Resist based armors, and yes, I would lean making these a Brute, /bio is going to pump out the most offense, but again, you need to minimalize the effects and that might not be enough. /rad is going to be a rolling nuke bomb via procs. Tough to minimalize, but it can be colored so there might be some colors which make it more tolerable.